A well-known shoe-hold apparatus is structured by comprising a shoe-hold spring, which is a sheet metal bent to form a web side arm and a drum side arm and has a pair of one end opened slots at ends of the arms, and a shoe-hold pin, which engages with the back plate.
This conventional shoe-hold apparatus is structured such that the shoe-hold spring is retained between a flattened engagement head of the shoe-hold pin and the web by next steps;    (1) the shoe-hold pin is penetrated through a pin-insertion hole formed in the back plate to engage the shoe-hold pin with the back plate,    (2) the shoe-hold spring is sled on a drum side surface of the web from a crossing direction with an axis of the shoe-hold pin so that the shoe-hold pin passes through the pair of slots.
Patent Reference 1 discloses the above-type shoe-hold apparatus. The shoe-hold apparatus described in the Patent Reference 1 is designed such that a concave seat is formed at a closed end portion of the slot, which is formed at each end of the pair of arms of the shoe-hold spring, and one of the concave seats is engaged with the engaging head of the shoe-hold pin in order to prevent a disengagement of the shoe-hold spring.
The shoe-hold apparatus is assembled by next steps:    (1) the shoe-hold pin is penetrated through the pin-insertion hole formed in the back plate to engage the shoe-hold pin with the back plate,    (2) the pair of arms of the shoe-hold spring are compressed and then the shoe-hold spring is pushed from a crossing direction with the axis of the shoe-hold pin along the web to move the shoe-hold sprig until the closed end portion of the slot of the shoe-hold spring reaches the shaft of the shoe-hold pin, and    (3) the force compressing the pair of arms is released to engage one of the concave seats with the engaging head of the shoe-hold pin.
Also, for another conventional shoe-hold apparatus, the Patent Reference 2 discloses the shoe-hold apparatus having the shoe-hold spring made of a sheet metal bent in P-shape to approach the web side arm to the drum side arm.
Patent Reference    [Patent Reference 1] U.S. Pat. No. 5,540,310 (FIGS. 1-3)    [Patent Reference 2] U.S. Pat. No. 6,062,354 (FIGS. 1-4)
The characteristics of the shoe-hold apparatus disclosed in the Patent Reference 1 are the concave seats, which are formed at the closed end portions of the pair of slots, and the bending portions, which are formed at the top ends of the pair of arms. The conventional shoe-hold apparatus has the following problems.    <1> An engagement portion, where the shoe-hold pin engages with the shoe-hold spring, is only one portion between the engagement head of the shoe-hold pin and one of the concave seats of the shoe-hold spring after assembly thereof, and no other engagement portions exist between the shoe-hold pin and the shoe-hold spring.
Therefore, if someone pulls the shoe-hold spring, for example, while the drum brake device is being carried (prior to the assembly of the drum brake device to the vehicle), the shoe-hold spring rotates with the engagement portion as the fulcrum, thereby creating a chance of disengaging the shoe-hold spring.    <2> In order to engage the engagement head of the shoe-hold pin with the seat of the shoe-hold spring, the shoe-hold spring needs to forcefully, resiliently be deformed equal to or more than the depth of the seat and to move the shoe-hold spring while maintaining the condition of resilient deformation to the end, thereby leaving a problem of extremely inefficient operability.
The shoe-hold apparatus described in the Patent Reference 2 has the following problems.    <1> In the shoe-hold apparatus in the Patent Reference 2, the distance between the pair of arms is set short, and therefore the invention in the Patent Reference 2 does not require bending portions at top ends of the pair of arms as like as required in the shoe-hold apparatus in the Patent reference 1.
However, the invention in the Patent Reference 2 has no concave seat as compared to the device of the Patent Reference 1, which facilitates the movement of the shoe-hold spring and creates a chance of disengaging the shoe-hold spring, and therefore the disengagement preventive effect of the shoe-hold spring after the assembly of the shoe-hold apparatus is not considered sufficient.